Electrical measuring instrument.



No. 698,680. 7 Patented Apr. 29, I902.

T. DUNCAN.

ELECTRICAL MEASURING TNSTRUMENT.

(Application filed. Jan. 2 1900. Renewed Dec. 16, 1901.)

(N0 Model.)

Ina-5525 THE NORms 'FETERS co, Puma-undo wnsnmsmu, n. c

Futon.

THOMAS DUNCAN, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE SIEMENS & HALSKEELECTRIC COMPANY OF AMERICA, OF CHICAGO, ILLINOIS, A

CORPORATION OF ILLINOIS.

ELECTRICAL MEASURING INSTRUMENT.

SPECIFICATION forming part of Letters Patent No. 698,680, dated April29, 1902.

Application filed January 2, 1900. Renewed December 16, 1901. Serial No.86,061. (No model.)

To all whom it may concern:

Be it known that I, THOMAS DUNCAN, a citizen of the United States,residing at Chicago, in the county of Cook and State of Illinois, haveinvented a certain new and useful Improvement in Electrical MeasuringInstruments, (Case No. 342,) of which the following is afull, clear,concise, and exact description,

reference being had to the accompanying drawing, forming a part of thisspecification.

Myinvention relates to compensating voltmeters, and has for its objectthe provision of improved means for determining the electromotive forceat any predetermined point of a system of distribution, my inventionenabling me to accurately secure this result.

When the pressure at any point distant from the generating-station isaccurately determined, this pressure may be maintained constant byregulation of theimpressed pressure to compensate for load changes andthe C R drop over the distributing-lines clue thereto, which variesdirectly as the load.

Two ways have hitherto been frequently practiced for measuring thepressure at a predetermined point in the line distant from thegenerating-station. A common way is to employ an ordinary voltmeter uponthe station-switchboard, which is connected at a distant point-as, forexample, the center of distrlbution-by means of two pressure-wires, theinstrument then indicating the pressure at the distant point. I/Vhen thedistance between the distant predetermined point of the line and thegenerating-station is great, the expense of these pressure-wires issignificant when a great number of machines are used. It has also beenthe practice to employ what are termed compound compensating voltmeterscontaining two windings, one a pressure-winding connected between thegenerator-terminals and the other a counter compounding or demagnetizingwinding comprising one or more turns of the series or main conductorupon the same voltmeterspool with the shunt-winding, the currentincreasing the counter magnetizing effect of the series winding as theload increases to give a resultant magnetizing effect, which indicatesthe pressure reduction in the transmission-lines. The number of turns ofthe series or current winding is dependent upon the percentage of dropin the mains. This latter method, however, is objectionable, since atrue compensation is not always effected in the meter for the c r drop,since the countermagnetizing effect of the series winding would be thesame irrespective of the distance of the load from the generator.

In practicing my present invention I am enabled to eliminate one or bothof the pressure-wires employed in one of the aforesaid prior methods, toreduce the cost of line construction, and at the same time maintainaccuracy in the determination of the pressure at the distant points ofdistribution where the pressure is to be measured.

In practicing my invention I employ a me ter having a winding connectedor adapted for connection between two distant points of the system ofdistribution, preferably between a point on one transmission-conductorat the generator-station and another point of the sametransmission-conductor at the distant place where the pressure is to bedetermined. A torque is created by this winding which is proportional tothe C R drop be tween the connected points. In mypresentinvention I alsoemploy a second winding, which is connected across thegenerator-terminals. I am also enabled to overcome the disadvantages ofthe second aforesaid prior method of determining the pressure at pointsdistant- 'from the generator-station, in that I am enabled to accuratelydetermine this pressure irrespective of the distribution of the load.

In my application, Serial No. 87, filed of even date herewith, I havedisclosed an apparatus for accomplishing the desired result in which apointer and a scale were associated with each of the windings, wherebythe C R drop and the pressure at the generator-terminals could beseparately measured. WVith my prior apparatus in order to ascertain thedifference in potential at the predetermined distant point twice the C Rdrop in one transmission-conductor was subtracted from the indicatedpressure at the generator-terminals, the portion of the apparatus formeasuring the C R drop in one transmission-line being so calibrated asto indicate directly the total C R drop, so that it was only necessaryto take the difference between the readings to determine the pressure atthe distant predetermined point.

My invention herein is an improvement upon the apparatus of my aforesaidapplication. in that I am enabled to provide an instrument capable ofgiving the pressure at any predetermined point of a transmissionline ina single reading. To effect this result, I preferably cause saidwindings to cooperate to effect a single movement proportional to thepressure at the distant point of the system. In the preferred embodimentof vthe invention the said windings jointly create a single torque andare mechanically coupled, being preferably mounted upon a commonoscillating shaft having a pointer movable therewith which is adapted toindicate the movements of the shaft upon a suitable measuring-scale. Theresultant action of the said windings is proportional to the algebraicsum of the pressure across the generator-terminals and the G R drop, thetorque due to the meter-windings acting in opposite directions.

I will explain my invention more particu larly by reference to theaccompanying draw ing, which diagrammatically indicates an instrumentconstructed in accordance with the invention and a system ofdistribution with which the said instrument is connected.

I have indicated a system for distributing direct current, a source ofdirect current a being shown as supplying current to translating devicesI). The instrument 0 may be constructed as shown, two field-poles d e ofsoft iron being preferably provided, a permanent horseshoe-magnet fbeing preferably employed, upon the ends of which said polepieces aresecured. An iron core g, which is preferably stationary, is disposedbetween the poles. A coil 71 of fine wire, mounted upon a rotatableshaft, surrounds the iron core and is disposed between the pole-pieces,this coil being included in circuit between the generator-terminals, aresistance 1 extraneonsto the said coil, beingincluded in thesamecrossconductor therewith to prevent waste of current through said coil.'A torque is thus prodnced proportional to the pressure of the generatorimpressed upon the transmissionmains. Torsional springs may be providedin the well-known way to oppose the torques of the instrument.

I have shown a pointer 7c, mounted to swing with the coil, and a scaleZ, upon which the measurements may be read. A second coil 'm ismechanically cou pied-with the aforesaid coil, the latter coil beingpreferably mounted upon the same shaft with the coil h. The coil m maybeincluded in bridge of a transmission-main, in this instance between theseparated points n and 0 at the generator and at a distant point of thetransmission system, respectively, an extraneous resistance p beingpreferably adapted for inclusion in the same circuit with the said coil.

I have shown a metallic pressure-conductor q for connecting the points nand 0. A part of this pressure-conductor may be replaced by groundconnections,if desired, as is well understood in the art. The point 0may be at the center of distribution or at the extreme end of the systemof distribution or a point between the extreme end and the center ofdistribution or at any-other point distant from the generating-station.If there is a load upon the circuit, a torque will be created in theinstrument due to the current flowing through the coil m. This torquebeing proportional to the O R drop and acting in opposition to the thetorque due to the winding h, the pointer will thereby indicate theresultant effect of the component torques due to said windings, therebymeasuring the pressure at the aforesaid distant point of thetransmission-circuit and not at the generator. If, for example, thedynamo-pressure is one hundred and four volts and the drop over thelines is four volts, then the resultant volts indicated on theinstrument will be 1044: 100. there will be no drop over thetransmissionlines, no current then flowing from the coil m, theinstrument then serving to measure the generator-pressure only. When aload is put upon the system, the current through the coil in will causea torque proportional to the drop over the line between theline-terminals of the coil m, this torque opposing the torque due to thecoil 71.

I preferably so adjust the windings of the instrument that the windingreceiving its current from the conductor q will produce relativelytwicethe torque for a given pressure impressed at its terminals thanthat caused by the winding subjected to the generating pressure.

In some of the claims I speak of the windings of the meter as beingconnected with the transmission-circuit and generator, and while I havespecifically disclosed the application of my invention to adirect-current system of electrical distribution I do not wish to belimited to conductive connections of the meter-windings with thetransmission-circuit.

\Vhile I have herein shown and particularly described one embodiment ofmy invention,

it is obvious that changes may be readily made without departing fromthe spirit thereof, and I do not, therefore, wish to be limited to theprecise construction shown; but,

Having thus described my invention, I claim as new and desire to secureby Letters Patent- 1. In a system of electrical distribution, the

combination with a generator supplying current to atransmission-circuit, of a measuring instrument having avoltmeter-winding connected across the generator-terminals, and a secondpressure-winding connected between a point of the transmission-circuitand a dis- WVhen there is no load on the dynamo,'

tant point of the transmission-circuit where the pressure is to bedetermined, and means whereby said windings may cooperate to produce asingle actuation of the movable element of the meter to measure thepressure at said distant point, substantially as described.

2. In a system of electrical distribution, the combination with agenerator supplying current to a transmission-circuit, of a measuringinstrument having a voltmeter-winding connected across thegenerator-terminals and a second pressure-winding connected between apoint of the transmission-circuit and a second distant point Where thepressure is to be determined, said windings cooperating to actuate themovable element of the meter to determine the pressure at said distantpoint, substantially as described.

3. In a system of electrical distribution, the combination with agenerator supplying current to a transmission-circuit, ofa measuringinstrument having a voltmeter-winding connected across thegenerator-terminals and a second pressure-winding connected between apoint of the transmission-circuit and a second distant point where thepressure is to be determined, said windings cooperating to produce aresultant torque upon the movable element of the meterto producemovement thereof to measure the pressure at said distant point,substantially as described.

4:. In a system of electrical distribution, the combination with agenerator supplying current to a transmission-circuit, of a measuringinstrument having a voltmeter-winding connected across thegenerator-terminals and a second pressure-winding connected between apoint of the transmission-circuit and a sec ond distant point where thepressure is to be determined, said windings being adapted each to createa torque opposing the torque due to the other whereby a resultant torqueis produced to actuate said element to measure the pressure at saiddistant point, substantially as described.

5. In a system of electrical distribution, the combination with agenerator supplying current'to a transmission-circuit, of a measuringinstrument having a voltmeter-Winding connected across thegenerator-terminals and a second pressure-winding connected between apoint of the transmission-circuit and a distaut point of thetransmission-circuit where the pressure is to be determined, saidwindings being mechanically coupled and rotatably mounted to jointlymeasure the pressure at said distant point, substantially as described.

6; In a system of electrical distribution, the combination with agenerator supplying cur-' rent to a transmission-circuit, of a measuringinstrument having a voltmeter-winding connected across thegenerator-terminals and a second pressure-windingv connected between apoint of the transmission-circuit and a distant point of thetransmission-circuit where the pressure is to be determined, said windings being mechanically coupled and rotatably mounted to jointly measurethe pressure at said distant point, an index-needle or pointer movingwith said windings, and a scale cooperating with the pointer to measurethe pressure at said distant point, substantially as described.

7. In a system of electrical distribution, the combination with agenerator supplying currentto a transmission-circuit, of a measuringinstrument having a voltmeter-winding connected across thegenerator-terminals and a second pressure-winding connected between apoint of the transmission-circuit and a distant point of thetransmission-circuit where the pressure is to be determined, saidwindings being mechanically coupled and rotatably mounted and producingcounteracting torques to jointly measure the pressure at said distantpoint, substantially as described.

8. In a system of electrical distribution, the combination with agenerator supplying current to a transmission-circuit, of a measuringinstrument having a voltmeter-winding connected across thegenerator-terminals and a second pressure-winding connected between apoint of the transmission-circuit and a distant point of thetransmission-circuit where the pressure is to be determined, saidwindings being mechanically coupled and rotatably mounted, and producingcounteracting torques,to jointly measure the pressure at said distantpoint, an index-needle or pointer moving with said windings, and ascalecooperating with the pointer to measure the pressure at saiddistant point, substantially as described.

9. In a system of electrical distribution, the combination with agenerator supplying current to a transmission-circuit, of a measuringinstrument having a voltmeter-winding connected across thegenerator-terminals and a second pressure-winding connected between apoint of the transmission-circuit and a distant point of thetransmission-circuit where the pressure is to be determined, said secondwinding being in shunt of a portion ofone side of thetransmission-circuit, and means whereby said windings may cooperate topro duce a single actuation'of the movable element of the meter tomeasure the pressure at said distant point, substantially as described.

10. In asystem of electrical distribution, the combination with agenerator'supplying current to a transmission-circuit, of a meas uringinstrument having a voltmeter-winding connected across thegenerator-terminals and a second pressure-winding connected'between apoint of the transmission-circuit 'and a seconddistant pointwhere thepressure is to be determined, said windingscooperating to actuate themovable elementof the meter to determine the pressure at said distantpoint, said second winding being inshunt of a portion of one side of thetransmission-circuit, substantially as described. I

11. In a system of electrical distribution,'

ICO

the combination with a generator supplying current-to a transmissioncircuit, of ameas urin g instrument having a voltmeter-winding connectedacross the generator-terminals and a second pressure-winding connectedbetween a point of the transmission-circuit and a second distant pointwhere the pressure is to be determined, said windings cooperatin g toproduce a resultant torque upon the movable element of the meter toproduce movement thereof to measure the pressure at said distant point,said second winding being in shunt of a portion of one side of thetransmissioncircuit, substantially as described.

12. In a system of electrical distribution, the combination with agenerator supplying current to a transmission-circuit, of ameasuringinstrument having a voltmeter-winding connected across thegenerator-terminals, and a second pressure-winding connected between apoint of the transmission-circuit and a second distant point where thepressure is to be determined,said windings being adapted each to createa torque opposing the torque due to the other, whereby a resultanttorque is pro duced to actuate said element to measure the pressure atsaid distant point, said second winding being in shunt of a portion ofone side of the transmission-circuit, substantially as described.

13. In a system of electrical distribution, the combination with agenerator supplying current to a transmission-circuit, of ameasuringinstrument having a voltmeter-winding connected across thegenerator-terminals and a second pressure-winding connected between apoint of the transmission-circuit and a distant point of thetransmission-circuit where the pressure is to be determined, saidwindings being mechanically coupled and rotatably mounted to jointlymeasure the pressure at said distant point, said second windingbeinginshunt of a portion of one side of the transmission-circuit,substantially as described.

14. In a system of electrical distribution, the combination with agenerator supplying current to a transmission-circuit, of a measuringinstrument havinga voltmeter-winding connected across thegenerator-terminals and a second pressure-Winding connected between apointof the transmission-circuit and a distant point of thetransmission-circuit Where the pressure is to be determined, saidWindings being mechanically coupled and rotatably mounted tojointlymeasure the pressure at said distant point, an index-needle or pointermoving with said windings, and a scale cooperating with the pointer tomeasure the pressure at said distant point, said second wind- .ing beingin shunt ofa portion of one side of the transmission-circuit,substantially as described.

15. In a system of electrical distribution, the combination with agenerator supplying current to a transmission-circuit, of ameasuringinstrument having a voltmeter-winding connected across thegenerator-terminals and asecond pressure-winding connected between apoint of the transmission-circuit and a distant point of thetransmission-circuit where the pressure is to be determined, saidwindings being mechanically coupled and rotatably mounted, and producingcounteracting torques, to jointly measure the pressure at said distantpoint, said second winding being in shunt of aportion of one side of thetransmission-circuit, substantially as described.

16. In a system of electrical distribution, the combination with agenerator supplying current to a transmission-circuit, of a measuringinstrument having a voltmeter-winding connected across thegenerator-terminals and asecond pressure-winding connected between apoint of the transmission-circuit and a distant point of thetransmission-circuit where the pressure is to be determined, saidwindings being mechanically coupled and rotatably mounted and producingcounteracting torques, to jointly measure .the pressure at saiddistant'point, said second winding being in shunt of a portion of oneside of the transmission-circuit, an index-needle or pointer moving withsaid windings, and a scale cooperating with the pointer to measure thepressure at said distant point, substantially as described.

17. In a system of electrical distribution,

the combination with a direct-current generator supplying current to atransmission-circuit, of a measuringinstrument having avoltmeter-winding conductively united with and included between thegenerator-terminals and a second pressure-winding conductively uniting apoint of the transmission-circuit with a distant point of thetransmission circuit where the pressure is to be determined, and meanswhereby said windings may cooperate to produce a single actuation of themovable element of the meter to measure the pressure at said distantpoint, substantially as described.

18. In a system of electrical distribution, the combination with adirect-current generator supplying current to a transmission-circuit, ofa measuring instrument having a voltmeter-winding conductively unitedwith and included between the generator-terminalsand a secondpressure-winding conductively uniting a-point of thetransmission-circuit with a second distant point where the pressure isto be determined, said windings cooperating to actuate the movableelement of the meter to determine the pressure at said distant point,substantially as described.

19. In a system of electrical distribution, the combination with adirect-current generator supplying current to a transmission-circuit, ofa measuringinstrument havinga voltmeter-winding conductively united withand included between the generator-terminals and a secondpressure-winding conductively uniting a point of thetransmission-circuit with a second distant point where the pressure isto be determined, said windings cooperating to produce a resultanttorque upon the movable element of the meter to produce movement thereofto measure the pressure at said distant point, substantiallyasdescribed.

20. In a system of electrical distribution, the combination withadirect-current generator supplying current to a transmission-circuit, ofa measuringinstrumenthavinga Voltmeter-winding conductively'united withand included between the generator-terminals and a secondpressure-winding conductively uniting a point of thetransmission-circuit. with a second distant point where the pressure isto be determined, said windings being adapted each to create a torqueopposing the torque due to the other, whereby a resultant torque isproduced to actuate said element to measure the pressure at said distantpoint, substantially as described.

21. In a system of electrical distribution, the combination with adirect-current generator supplying current to-a transmission-circuit, ofameasuringinstrumenthavinga voltmeter-winding conductively unitedwithand included between the generator-terminals and a secondpressure-winding oonductively uniting a point of thetransmission-circuit with a distant point of the transmission circuitwhere the pressure is to be determlned, said windings being mechanicallycoupled and ro-.

tatably mounted to jointly measure the pressure at said distant point,substantially as- THOMAS DUNCAN. Witnesses:

WILLIAM F. MEYER, JAMEs IV. DALTON.

